In a wireless communication system, such as the General Packet Radio Service (GPRS), the Base Station System (BSS) can request a Packet Downlink Ack/Nack (PDAK) by polling on a downlink data block. The mobile can then request uplink resources, when needed, by sending a channel request in the PDAK. After sending a channel request, the mobile will start a first timer. The value for the duration of the first timer is set by the network in system information messages. In GPRS, it can range from a minimum of 500 ms to a maximum of 4 seconds (e.g., for heavily congested systems). If the mobile does not receive a Packet Uplink Resource Assignment (PUA) after sending a channel request in the PDAK, the mobile will not send a new channel request in another PDAK until either the first timer expires or a Packet Access Reject message (PAR) is received. The reason for not allowing a new channel request before the first timer expires is to prevent the mobile unit from sending multiple channel requests in a rapid sequence before the base station has had time to respond to the original channel request, thereby potentially overloading the base station with the additional, unnecessary channel requests. In the prior-art GPRS, the Packet Access Reject message (PAR) is sent only when the system is congested and there are no more uplink resources available to allocate to a mobile that is requesting uplink access through a channel request in the PDAK. Upon receipt of the PAR, the mobile starts a second timer for a duration of a WAIT_INDICATION value sent with the PAR by the network. The mobile is not allowed to make another attempt for packet access in the same cell until the second timer expires. It may attempt packet access in another cell after a successful cell reselection.
Under certain circumstances, this can cause the following problem. If a PDAK containing a channel request is missed at the network (e.g., due to uplink interference), a new channel request will not be initiated for the duration of the first timer (500 ms to 4 sec). Depending upon the value of the first timer, the delay between the network missing the PDAK containing the channel request and the arrival of a first uplink data block (upon a successful uplink resource allocation on a next subsequent channel request in a PDAK received from the same mobile) will be in the range of 680 to 4180 ms (for the GPRS system). This will substantially degrade the data transfer rate.
Thus, what is needed is a method and apparatus in a wireless communication system for expediting a request from a mobile unit for uplink resources. The method and apparatus preferably will not require any modification to the protocol standards currently employed by the wireless communication system.